Brush holder for dynamos



June 3, 193,0. T, s BINDSCHEDLER ET AL 1,761,066

kINVENTOR BRUSH HOLDER FOR DYNAMOS Filed OCT.. 4, 1924 EIWI- mi! lill/-j Nm J 1 M Mw www ATTORNEY Patented 4June 3, 1.936`

UNITED STATES,

PATENT OFFICE THEODORE AS. BINDSCHEDLER, OF DETROIT, AND PETER J'.ROSTER, OF PLEASANT RIDGE, MICHIGAN, ASSIGNORS TO BURROUGHS ADDINGMACHINE COMPANY, A A

CORPORATION 0F MICHIGAN BRUSH HOLDER Foa DYNAM'os l Application led'0ctober 4, .1924. Serial No. 741,758.

This invention relates to a brush holder for electric motors and thelike and its urpose is to provide an improved holder w ich is adjustablefor the purpose of varying the torque produced by the motor. Theprincipal object of the invention is to provide a brush holder mountedfor angular movement on the casing of the motor andcapable of'adjustment for increasing or decreasing the torque by varying the pointsof commutation with respect to the magnetic eld, Another ob ject is toprovide a brush holder comprising a supporting bracket having mountedthereon a plurality'of brush holding devices which are interchangeablewith each other. Still another object is to provide means whereby motorsmay be employed with an unusual range of voltage and of cycle variation.Anothervfeature 1s the provision of means for permittin the removal ofthe brushes without distur ing the setting of the holder with respect tothe armature of the motor. The apparatus also comprises means forpreventing the accidental removal of the brushes from the holders whenthe armature and cpmmutator are removed from the motor casing. A furtherimportant object of the invention is to provide improved means forforming anelectrical contact between the electrical supply conductorsand the brush proper without the-necessity of using auxiliary shuntwires. The improved brush holder comprises improved means for making apositive connection between thexsupply conductors and the brushes-andthe simplified construction permits the use of stampmgs formed ofmaterial having high electrica-l conductivity, such as bronze, brass,copper and the-like.

The nature of the invention will be more fully understood from thefollowing specification taken with the accompanying drawings, inwhich'lF 1 is a section on the line 1-1 of Fig. 2,100 ing in thedirection of the arrows, showing the relation' of the brush holder tothe armature of the motor; Fig. 2 is a fragmentary section taken on theline 2 2 ofFig. 1 showing a top plan view of gne of the brush aholdersand a sectional v1ew through the casing of the other brush holder; Fig.3 is an enlarged section on the line 3-3 the plane of the armatureshaft, a portion of f the holder being broken away; Fig. 6 is aperspective view of the brush holder bracket;

and Fig. 7 is a partial inside elevation of the'.

end wall of the dynamo casing with the brush holder, brushes andarmature removed.

The invention may be employed in connection with electric dynamos ofvarious types, but is illustrated in the drawings in connection with anelectric motor comprising a casing 10 having an end wall 11 providedwith a bearing 12 for the armature shaft 13` on which -is mountedthearmature and the commutator 15. The end wall 11 of the motor casing isprovided with an annular flange 16 on which is mounted the brush holdersupporting bracket 17, having the form shown particularly in Fig. 6.This bracket comprises a plate having formed vtherein a curved notch oraperture 18 adapted to coact with the outer surface of the flange 16 sothat the bracket may be adjusted angularly to vary the positions of thepoints of commutation with respect to the magnetic field of the motor.The bracket 17 is secured in adjusted position by means 'of a clampingbolt or setl screw 19 engaging an aperture 20 in the bracket and anelongated slot 21 formed in the end wall 11 of the motor casing. Thebracket 17 is further provided with two outwardly extending flanges 23each of which carries a brush holderdesignated by the numeral 24. Eachbrush holder is made -up of ltwo 'complementary plates 25 and 26 whichare provided with laterally extending ears 25* and 26 respectively,having holes therein to be engaged by the bolts 27 which extend throu hapertures 28 in the anges 23, the bolts. eing insulated from the flangesof the longitudinal guideway 32 of rectangular cross-section which visformedvas a groove or recess in the plate 25, and which is adapted toreceive and be closely titte-d by a brush 33, formed of carbon or thelike, which projects downwardly -through the lower end of the brushholder` and contacts with the peripheral surface of the commutator 15.The flanges 23 on the bracket are preferably so arranged that thelongitudinal axes of the brushes 33 are inclined to the radii of thearmature in the direction in which the commutator rotates, this beinganti-clockwise, as viewed in Fig. 1. Each brush 33 is provided at itsouter end with a cylindrical projection 34 having the same diameter asthe thickness of the brush, as shown in Figs. 3 and 4, and each of theselugs 34 has secured thereto the inner end of a coil spring 35. Thesesprings project slightly beyond the edges of the brushes and are adaptedto slide in grooves 36 and37 which are formed in the plates 25 and 26,re-

spectively, by pressing or stamping outwardly the metal of these plates.The grooves 36 and 37 terminate above the inner ends of the brushholders, thereby forming shoulders 38 which are adapted to engage theinner ends of thev springs 35, when the arma-ture is removed from themotor or when the brushes become greatly worn, so that the accidentaldropping outof the brushes is prevented and the extent of inwardmovement is limited.y

f The outer end of each spring is secured pressed positions, whereinthey maintain the A brushes 33 in contact with the armature 15, by meansof yokes 42, each comprising a curved plate 43 adapted to pass over theouter end of each brush holder, and two lateral arms 44 which extenddownwardly on opposite sides of the brush holder, as shown particularlyin Fig. 3. These arms are provided at their inner ends with lugs 45having a pivotal engagement with notches 46 formed in the plates 25 and26 so that the yokes can be moved toward and from their normalpositions. 42 is limited by the flanges 47 Awhich project inwardly fromthe outer ends of the plates 43 so that when the yokes are in theirnormal positions, as shown in Fig. 3, theflanges 47 engage the sides ofthe guideways 32 and When in this position, each yoke is held againstremoval by the engagement of the rounded head 40a of the adjacent springcap with an aperture 48 formed in the plate 43.

When the yokes are moved toward the left, as viewed in Fig. 5 afterreleasing the parts 402l from the recesses 48, the springs 35 ex# pandand the brushes may then be wlthdrawn The extent of movement of theyokes outwardly through the guideways 32, using the springs as handles.

An electrical connection is made to each brushholder through angesl 5()which are formed on the plates 25 and which are adapt'- ed to beconnected to the supply conductors 51 through which the electric currentpasses to the brushes. A ange 50 is formed on each side of each of thebrush holders so that they may be interchanged with each other, theconnection being made to the innermost flange of each holder. It will beapparent that the design of the bracket 17 is such that the two brushholders are mounted substantially ninety degrees apart and the flanges50 extend downwardly so that the electrical connections to theconductors 51 are made from below, as illustrated in Fig. 1. A positiveelectrical connection is ma'dc'from the casing of each holder 24 to itsbrush through the yoke 42, cap 40 and spring 35 so that it 1sunnecessary to depend on the contact of the brushl with the walls of theguideway 32 and the use of auxiliary shunt wires is not required. Theend casing 11 of the motor is preferably provided with an aperture l1athrough which access may be had to the brush holders and the supportingbracket, this opening being normally closed by a suitable cover. I

Electric motors equipped with this invention may be'adapted to varioususes but they may be employed with'particular advantage in connectionwith adding machines where it is desirable, by a simple adjustment, toadapt an electric motor, such as a series wound motor of the universaltype, to the driving of adding machines of ditferent capacity. This maybe accomplished by adjusting the bracket 17 in order to vary the angularposition of the brushes on the commutator and thereby alter the currentpassing through the armature in different parts of the magnetic fieldfor the purpose of varying the torque produced on the motor shaft. If itbe desired to increase the torque of the motor, the brush holdingbracket may be adjusted in a clockwise direction, as viewedin Fig. 1,and if it be desired to decrease the torque of the motor the brushes maybe readily adjusted in a counterclockwise direction. When the vinvention is applied to a generator, the effect ofthe angular adjustmentwill be to vary the terminal voltage together with the armaturereactions and to produce other electrical and magnetic effects as willbe apparent to those skilled in the art.

Although one form of the invention has been shown and described by wayof illustration, it will be understood that it may be constructed invarious other embodiments withoutdeparting from the scope of theappended claims.

We claim:

1. In combination, a dynamo having a casing provided with a flange, aplate extending throughout a portion of the periphery of said flange,said plate lying in a plane normal to the axis of the dynamo. means foradjusting said plate on said flange about said axis, arms formedintegrally with and extending transversely to said plate, and brushholders mounted on and insulated from said arms.

2. In combination, a dynamo easing having an annular flange, a platehaving oppositely directed hook members adapted partially to surroundsaid flange, means for securing saidv plate in adjusted position, a pairof arms extending transversely from opposite sides, of said plate, brushholders carried by and insulated from said arms, and brushes slidablymounted in said brush holders.I

3. In combination a brush holder having a guideway therethrough, a brushmounted in said guideway, a spring mounted in said v guideway andconnected to said brush, and shoulders formed on said brush holder forengaging the end of said spring to limit the movement thereof.

THEODORE S. BINDSCHEDLER. PETER J. KOSTER.

